sourceJlo=pj(1)*targetIlo+pj(2)*targetJlo+oj
sourceJhi=pj(1)*targetIhi+pj(2)*targetJhi+oj
INTEGER pi(2), pj(2), oi, oj, tN
pj(1) =exch2_pj(1,N,myTileId)
pj(2) =exch2_pj(2,N,myTileId)
DO pj = 1, nPy
bj0(pj) = pj
INTEGER bi, bj, pi, pj